Determination of elastic properties of consolidated nanocrystalline alloys iron–copper by means of acoustic echography and interferometry

2003 ◽  
Vol 48 (5) ◽  
pp. 531-537 ◽  
Author(s):  
H.S Cao ◽  
R Bonnet ◽  
J.J Hunsinger ◽  
O Elkedim
2018 ◽  
Vol 233 ◽  
pp. 00025
Author(s):  
P.V. Polydoropoulou ◽  
K.I. Tserpes ◽  
Sp.G. Pantelakis ◽  
Ch.V. Katsiropoulos

In this work a multi-scale model simulating the effect of the dispersion, the waviness as well as the agglomerations of MWCNTs on the Young’s modulus of a polymer enhanced with 0.4% MWCNTs (v/v) has been developed. Representative Unit Cells (RUCs) have been employed for the determination of the homogenized elastic properties of the MWCNT/polymer. The elastic properties computed by the RUCs were assigned to the Finite Element (FE) model of a tension specimen which was used to predict the Young’s modulus of the enhanced material. Furthermore, a comparison with experimental results obtained by tensile testing according to ASTM 638 has been made. The results show a remarkable decrease of the Young’s modulus for the polymer enhanced with aligned MWCNTs due to the increase of the CNT agglomerations. On the other hand, slight differences on the Young’s modulus have been observed for the material enhanced with randomly-oriented MWCNTs by the increase of the MWCNTs agglomerations, which might be attributed to the low concentration of the MWCNTs into the polymer. Moreover, the increase of the MWCNTs waviness led to a significant decrease of the Young’s modulus of the polymer enhanced with aligned MWCNTs. The experimental results in terms of the Young’s modulus are predicted well by assuming a random dispersion of MWCNTs into the polymer.


2020 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Carlo Boursier Niutta

A new approach for the nondestructive determination of the elastic properties of composite laminates is presented. The approach represents an improvement of a recently published experimental methodology based on the Impulse Excitation Technique, which allows nondestructively assessing local elastic properties of composite laminates by isolating a region of interest through a proper clamping system. Different measures of the first resonant frequency are obtained by rotating the clamping system with respect to the material orientation. Here, in order to increase the robustness of the inverse problem, which determines the elastic properties from the measured resonant frequencies, information related to the modal shape is retained by considering the effect of an additional concentrated mass on the first resonant frequency. According to the modal shape and the position of the mass, different values of the first resonant frequency are obtained. Here, two positions of the additional mass, i.e., two values of the resonant frequency in addition to the unloaded frequency value, are considered for each material orientation. A Rayleigh–Ritz formulation based on higher order theory is adopted to compute the first resonant frequency of the clamped plate with concentrated mass. The elastic properties are finally determined through an optimization problem that minimizes the discrepancy on the frequency reference values. The proposed approach is validated on several materials taken from the literature. Finally, advantages and possible limitations are discussed.


2012 ◽  
Vol 45 ◽  
pp. S19
Author(s):  
A. Wittek ◽  
P. Bihari ◽  
A. Shelke ◽  
T. Nwe ◽  
K. Nelson ◽  
...  

Author(s):  
B.G. Tsugkiev ◽  
◽  
L.Ch. Gagieva ◽  
T.V. Tsugkieva ◽  
M.M. Chegaev ◽  
...  

The paper presents a comparative assessment of the nutritional value depending on the phenological phase of Onobrychis viciifolia Scop., as well as the determination of the regularity of the accumulation of biologically active substances and heavy metals in the herb of the species. The yield of green mass of plants was determined. From each hectare of sowing, 9,7 centners of protein can be obtained; the yield of fiber is 13 centners, BEV is 22,9 centners, fat is 1,6 centners, ash is 4 centners and carotene is 13.0 kg. Depending on the growing season, the chemical composition in the grass of Onobrychis viciifolia changes. The content of calcium, phosphorus increases, and the presence of iron, copper, cobalt, zinc, manganese and molybdenum and amino acids decreases.


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